It is known that the combustion and the pollutants emission of an internal combustion engine get worse at cold. For a long time, to reduce the warm up time, the cooling system of an ICE is equipped with a thermostatic valve to exclude the radiator, so that the engine is not cooled until the water stored in it reaches a target temperature, e.g. a temperature around 90° C.
The functional core of known thermostatic valves generally used in the automotive field is a thermostatic expansion element, e.g., a wax element connected to a main valve plate via a piston and contrasted by a spring. The wax element must be always wet by warm water coming from the engine. Around the target temperature, the wax changes its status from solid to liquid expanding its volume as well, pushing on the piston and opening the valve. The spring keeps the valve closed until the target temperature is reached. To improve the behavior of the valve, it is known to use an electrical heater directly acting on the wax.
At the first opening of the thermostat, the water stored in the radiator is much colder with respect to the water circulating in the engine (up to Δt>110° C.). Consequently, when the cold water from the radiator hits the wax element, the thermostat starts to close very quickly. The consecutive increase of temperature due to the hot water from the engine induces the thermostat to a new opening, so that cold water starts to flow again in the engine. This instable behavior of the thermostat causes a temperature instability until the achievement of a thermal steady state.
At least one object herein is to provide a thermostatic valve assembly that reduces, or even prevents, the temperature instability of the cooling fluid in the cooling system of an internal combustion engine when the thermostatic valve assembly starts to open.
Another object is to provide a thermostatic valve assembly that automatically controls sudden changes of temperature and pressure of the cooling fluid in the cooling system of an internal combustion engine. In addition, other objects, desirable features and characteristics will become apparent from the subsequent summary and detailed description, and the appended claims, taken in conjunction with the accompanying drawings and this background.